This invention relates to an image enhancement system for high addressability printing and, more particularly, to an apparatus for enhancing image data through pulse width modulation and delayed phase signals to improve subpixel addressability.
Digital reproduction, transfer or display of original images on image output terminals begins by creating a digital representation of an original image. Commonly, the digital representation becomes a bitmap in which multiple grey levels in the original image are reproduced by varying the spatial frequency of halftone dots. Continuous tone images or image portions are typically represented in binary form by creating these halftone dots, where each dot represents a grey level density within an area of picture elements (pixels).
A continuing goal in the art is to improve the image quality of printers. Pulse width modulation is one high addressability technique to increase printer resolution without modifying the physical printer device. Images are stored in the form of image data, the image data being represented by pixels. To increase the resolution, each pixel is divided into N subpixels.
High addressability systems typically have two solutions, each with its own problems. One high addressability system will provide high resolution placement and width modulation of the subpixels but has a limited data bit rate. The other high addressability system will provide multiple subpixel placement with a high data bit rate but with undesirable side effects relating to electromagnetic compatibility.
It is an object of this invention to provide an apparatus for enhancing image data for a high addressability printing system with a high data bit rate and high speed with electromagnetic compatibility.